Grinding-bur.



J. H. LETZ.

' GRINDING BUR. APPLICATION FILED MAY 7. 1917.

1,244,517. Patented on. 30,1917'.

2552, a JJM f@ fff/f ff jf@ ff ff 2 JOHN HOLLAND LETZ, 0F CROWN POINT, INDIANA, ASSIGNOR T0 THE LETZ MANU- FACTURING COMPANY, 0F CROWN POINT, INDIANA, A CORPORATION OF INDIANA.,

GRINDING-BUR.

To all whom t may concern.'

Be itknown that I, JOHN HOLLAND Ln'rz, a citizen of the United States. and a resident of Crown Point, in the county of Lake and State of Indiana, have invented certain new and useful Improvements lin Grinding-Burs, of which the following is afull, clear, and exact specification.

My invention is concerned with grinding burs of the class in which an annular base plate is provided with plural series of ribs projecting upward therefrom to a uniform height and having their tops ground off fiat to `Yform shearing edges to coperate with shearing edges on the similar ribs of the companion bur, and is designed to produce a bur having a novel design and arrangements of the ribs that will adapt it especially to grind oily stuii', such as cottonseed, beans, corn, oats, etc.

T o illustrate my invention, I annex hereto a sheet of drawings, in which the same reference characters are used to designate identical yparts in all the figures, of. which,

Figure l is a plan view of a portion of the bur sufiicient to show the design of one complete section; and

Fig. 2 is a central cross section on a reduced scale.

The bnr has an annular base A, which is preferably a casting, with the central portion B surrounding the central feeding aperture depressed as shown. The back is provided with the customary annular ribs C and D.

The grinding ribs are preferably arranged in six similar groups, so that a description of one group will serve for all. Of the generally parallel inner ribs E, F, G, H, I and J, the ribs E, F and Gr have their inner ends straight and extending toward the feeding aperture so as to receive and distribute the grain to the section. The outer ends of all these ribs are provided with right-angular portions set at an angle to the general direction of the rib, which general direction is at an acute angle to a central radial line of the section. The inner ends of the ribs H, I and J are also provided with similarrightangular extensions, which, h owever, are' oppositely directed, so that the 1nner ends serve as guides to direct the materials to be ground into the channels formed between any -r1b and its adjacent generally parallel ribs.

Between the outer ends of the long ribs Specication. of Letters Patent.

Application led May 7, 1917. Serial No. 166,897.

are the short rectangular ribs, K, L, M, N and 0, these ribs serving mainly as baffle ribs to slow up the movement of the grain and direct it into the final channels formed by the outermost series of long ribs I), Q, R,

S and T, the longer of which are provided at their inner ends with the right-angular extensions. The bodies of these last-named ribs reach to the periphery, and coperating with them to prevent the too rapid escape of grain from the periphery, are the small rectangular substantially radially arranged ribs U on the periphery.

What I claim as new, and desi-re to secure by Letters Patent of the United States, is:

l. A grinding bur comprising the annular base portion, with plural series ofv ribs projecting therefrom and having the flat tops forming shearing edges, each of said series composed of a set of generally parallel elongated' inner ribs set at an acute angle to a central radial line of the section containing the series, an outer set of shorter ribs eX- tending generally parallel to the inner set and having the same number so as to form continuations thereof, and an intermediate set of very short ribs in staggered relation to the adjacent `ends of the other two sets of ribs, the ribs of each of said sets being physically separated from the ribs of the other sets, substantially as shown and described.

2. A grinding burvcomprising the annular base portion, with plural series of ribs projecting therefrom and having the fiat tops forming shearing edges, each of said series composed of a set of generally parallel elongated inner ribs set at an acute angle to a central radial line of the section containing the series, an outer set of shorter ribs extending generally parallel to the inner set and having the same number so as to fcfm continuations thereof, and an intermediate set of very short ribs in staggered relation to the adjacent ends of the other sets of ribs, the outer ends of the inner set and the inner ends of the outer set of ribs having the right-angular extensions set at an. angle to the general direction of the ribs, the ribs of each of said sets being physically separated from the ribs of the other sets.

3. A grinding bur comprising the annular base portion, with plural series of ribs projecting therefrom and having the fiat tops forming shearing edges, each of said series composed of a set of generally parallel elongated inner ribs set at an acute angle toa central radial line of the section containing' the series, an outer set of shorter ribs eX- tending generally parallel to the innerset and having the same number so as to form continuations thereof, an intermediate set of very short ribs in staggered relation to the adjacent ends of the other two sets of ribs, the ribs of each of said sets being phys- 10 ically separated from the ribs of the other sets, and short ribs on the periphery between the ends of the outer set of ribs, substantially as shown and described.

ln witness whereof, I have hereunto set my hand and aflixed my seal, this 26th day l5 of April, A. D. 1917.

J H N HOLLAND LETZ. Vit nesses JOHN E. FRAAS, JACOB J. STEELE. 

